Circuit breakers with rocking prebiased contacts



Aug. 17, 1965 A. R. NORDEN Original Filed Feb. 26, 1958 a; O Z

I 52 55 l '1 54 74 I II i 56 7 6 S if: 60 24 H G 1 a Y I 7 53 22 l 2 2 r /2 x mu v INVENTOR 1454 44 95? 2. flazpi/v BY pawn/M ATTORNEY United States Patent 3,201,554 CIRCUIT BREAKERS WITH ROCKING PRE- lElASEl) CQNTACTS Alexander R. Norden, New York, N.Y., assignor to Federal Pacific Electric Company, a corporation of Delaware Original application Feb. 26, 1958, Ser. No, 717,647, new Patent No. 3,126,592, dated Feb. 4, 19:64. Divided and this application Mar. 15, 1%3, Ser. No. 272,176 3 Claims. (Cl. 200-166) This application is a division of my application Serial No. 717,647, filed February 26, 1958, entitled Circuit Breakers for Panelboards, now Patent No. 3,120,592.

The present invention relates to circuit breakers, especially for mounting on standard circuit breaker panelboards.

Circuit breaker panelboards, particularly the plug-in type such as that of the type disclosed in US. Patent 2,647,225, issued July 28, 1953, to T. M. Cole et al., have gained great popularity and are in Widespread use. This success in part may be attributed to the fact that both the panelboard and the circuit breakers are manufactured as standard items, the circuit breakers being supplied in a variety of ratings (to a maximum) to be selected and mounted on the panelboard as required by each particular installation and without requiring any individual attention by the manufacturer to the particular job. The standardized circuit breakers for each manufacturers panelboard have the same physical proportions (per pole) regardless of rating, up to a maximum, and the panelboard is designed to operate according to established safety standards when fully equipped with the standard circuit breakers.

An object of the present invention is to provide a novel form of circuit breaker having .a heavier per-pole current rating than the maximum standard circuit breakers available for use with the standardized panelboards, without however interfering with the versatility or flexibility of the standardized panelboards or with their meeting established standards. Previous standard circuit breakers and the novel circuit breakers can be used in accordance with job requirements without any special attention by the manufacturer to each job requirement.

Panelboards for circuit breakers are commonly designed to be energized from different phases of an alternating current supply. Where center-tapped single phase service is furnished, the center tap is arranged as a neutral and the two outside wires of the supply are referred to as phases; and this term is also used to designate the separate supply lines of a three phase power supply for which other standard panelboards are designed. Both single-phase and three-phase panelboar-ds are sequence-phased, that is, the bus terminals of both classes of .panelboards are subdivided, iadjacent portions of the subdivided bus terminal assembly being adapted for connection to the diiierent phases of the supply. The adjacent poles of multipole circuit breakers mounted at a subdivision of the bus can then be energized by different phases of the supply. According to a further feature of the invention, a novel multipole circuit breaker is provided for mounting on a standard sequence-phased panelboard where the rating of the individual poles of the multipole circuit breaker is heavier than the maximum safe standard individual pole rating for which the panelboard is intended, while at the same time insuring approved operation of the panelboard according to established standards.

The nature of the invention and further features of novelty and other aspects of the invention will be better appreciated from the following detailed description of an illustrative embodiment thereof, shown in the accompany- @atented Aug. 17, 1965 ing drawings forming part of the disclosure of the inv ntion. In the drawings:

FIG. 1 is the plan view of a circuit breaker panelboard of standard design, bearing circuit breakers of standard design together with an illustrative form of a two-pole circuit breaker embodying features of the present invention; and

FIG. 2 is an enlarged cross-section of the apparatus in FIG. 1 taken along the line 2--2.

A panel assembly is shown in FTGURES 1 and 2 of the type in the aforementioned Cole et al. patent. This panelboard is of a form to receive two rows of single pole circuit breakers with four single-pole circuit breakers in each row; or, alternatively, the standard panelboard i adapted to receive one two-pole circuit breaker in each row and, additionally, two single pole circuit breakers in each row. Two-pole circuit breakers suitable for use here may be of the type in the Christensen et al. Patent 2,662,949 issued December 15, 1953. Two-pole circuit breakers are characterized by having two circuits that are entirely electrically separate and which are commonly designated poles. Each pole includes a line terminal, a load terminal, a pair of contacts which are closed and opened to make and break the circuit from the supply terminal to the load terminal, and an overload release element. The poles of a two-pole circuit breaker have a common operating handle and each pole may have its separate operating mechanism, or a single contact operating mechanism may be provided for all of the poles. The overload release means of each pole in any case causes automatic opening of the contacts of the several poles upon detection of an overload in any one pole. While the discussion of poles above refers to singleand two-pole circuit breakers, it is fully applicable to three-pole circuit breakers.

The panelboard in FIGS. 1 and 2 is designed for the usual three-Wire single phase power distribution system. A three-phase sequence-bussed panelboard such as that in my Patent No. 2,739,272 issued March 20, 1956, will naturally be used with the three-pole circuit breaker.

The illustrative panelboard for receiving the circuit breakers includes a terminal pan assembly comprising a mounting pan it) having a series of integral hooks 12 at the lateral edges as viewed in FIG. 1. A terminal assembly generally designated 14 includes a member 16 of molded insulation having a downward projection 18 that fits into a corresponding hole in pan id and lateral projections 26' that are engaged by overhanging lane-es 22 integral with pan 1d. Lances 22 prevent the molded member 16 from being lifted away from the pan, and projection 18 of member 16 prevents the molded member from sliding lengthwise out of engagement with retaining lances 22.

Insulating member it? supports a pair of terminal members 24 and 2.6, which are designed to be connected as by screw connectors 28 and 30 to the two outside legs or phases of a three-wire single phase alternating current power line. Terminal members 24 and 2e are secured to insulating member 16 by screws 32 that extend from the bottom of the molded member 16 up into respective threaded openings in the members 24 and 26. Further, each terminal member 24 and 26 includes a series of formations 3 which constitute individual bus terminal formations complementary to the individual terminals of the circuit breakers mounted by the mounting pan and terminal assembly. In the embodiment shown in the drawings, the formations 3d are in the form of slots which receive male plug-in terminals of the illustrative circuit breakers; but in another widely used form of plug-in circuit breaker, the terminal formations of the panelooard are male members or blades that are complementary to resilient metal clips constituting the plug-in terminals of the circuit breakers. Such male panelboard terminal formations or blades may be disposed in the same directionas the slots 34 or they may extend across the terminal assembly 14, at right angles 'to the shown elongated slots 3d that they would replace. V

One retaining hook 112 and one formation 34 are provided for cooperating with each pole of the circuit breakers mounted by the mounting pan and terminal assembly shown. In the illustration, pan 1% provides two rows of circuit breaker receiving areas 110A at opposite sides of the terminal assembly 14, four such areas being shown on each side of the terminal assembly. A. pair of single-pole circuit breakers as appear in the bottom areas NA in the two rows of circuit breaker receiving areas. The terminal formations 34 that cooperate with the male plug-in terminals (not shown) of those bottom two circuit breakers 36 are both in one portion 38 of the terminal member 36, inasmuch as the bottom two circuit breakers 36 are properly connected to the same phase. A pair of terminal formations 34 are similarly available for mating with the plug-in terminals of the top pair of circuit breakers 35 in FIG. 1 at opposite sides of the terminal assembly 11 i. Terminal members 24 and 26 embody additional portions 42 and 4d respectively for respective poles of circuit breakers at opposite sides of the terminal assembly 14. Terminal portions 42 and 44 are of different phases,

far

and they are adjacent'each other, so that a two-pole circuitbreaker having a pair of stab plug-in terminals, of the form in the Christensen et al. patent mentioned above, can be mounted in either the left-hand row or the right-hand row of areas 16A of the mounting pan; 7

and each of the poles of the two-pole circuit breaker thus mounted would be connected to respectively different phases. 7 At this point, the terminals of the panelboard are said to be sequence-phased. It is evident that the terminals provided by the terminal assembly 14 could be 100% sequence-phased, by connecting areas 4th, 42, 44 and 38 in my patent mentioned above. That panelboard has two rows of circuit breaker receiving areas WA, and there as here the pairs of opposite'poles (one pole in each row) are connected to the same phase bus.

The load or current capacity for which the panelboard and terminal assembly of FIG. 1 may be rated depends to a large extent on the current carrying capacity of the bus terminals provided. Correspondingly, the bus terminals must be of sufficient capacity to accommodate the full complement of circuit breakers 36, Within the standar-d range of ratings of circuit breakers of that outline. Thus, the terminal assembly illustrated as well as the entire mounting pan and terminal assembly illustrated may be rated for 100 amperes to accommodate a typical complementof circuit breakers 36 whose ratings may be any combination of valuesbetween 15 and 50 amperes.

In accordance with features of the present invention, circuit breakers 46 are provided for heavy currents having enclosures proportioned to be mounted on the standard mounting pan assembly illustrated, without however exceeding the rating of the panelboard. The novel twopole circuit breaker illustrated includes one pair of male or stabterminals 48. of one pole thereof that mate with portion 42 of terminal member 24, and a similar pair of stab'term inals 43 are provided for the other pole of the circuit breaker, to mate with terminal portion 44 of the bus assembly. In this way, the standard panelboard can receive a two-pole circuit breaker at one side of the terminal assembly 14, in the space provided for two single poles; and this circuit breaker may be rated at 100 amperes, for example, without danger of overloading the panelboard. The heavy-current circuit breaker 46 engages not only the terminal formations 34 associated with the circuit breaker receiving areas 10A in the row which it occupies but also the terminal formations 34 associated with the circuit breaker receiving areas NA in the other row, at the opposite side of the terminal assembly 14. Each pole of the novel circuit breaker 46 with its dual plug-in terminal fullyoccupies an arealtiA and additionally 'preempts part of the opposite circuit breaker receiving area 10A of the opposite row of circuit breaker receiving areas 10A. This prevents mounting of a circuit breaker or a pair of circuit breaker poles in those areas 10A in the row opposite that wherethe circuit breaker has been mounted. It is evident also that the dual circuit breaker plug-in terminal 48 has proportionately greater contact surface engaging the terminal 14, and twice the curent-carrying capacity of a single circuit breaker stab that engages a single slot 34, and the multiple circuit breaker retains the side-by-side arrangement of coordinated poles and may be mounted to engage the respectively different phases of the panelboard bus assembly.

One of the poles of circuit breaker 36 is shown in FIG. 2 in broken-away cross-section. In that view, a screw connector St is shown at the end of the enclosure 52 of molded insulation remote from dual terminal 48; and this screw terminal 5% is joined by metal braid 51 to a resiliently mounted contact 54. Spring 55 biases contact 54 downward in the illustration. When the companion movable contact 56 is removed, the travel of the contact 54 is limited by shoulders 58 formed integrally in the molded enclosure 52. a i 3 Contact 56 is carried by a movable arm 59 as of copper 'to which there is united a current responsive bimetal 6t Contact arm 59 is' pivoted on a rigid pin 62 journaled in the casing. Contact arm 59 is operated by a linkage including latch 64 and other elements not here shown, but which are, for example, of the form in the abovementinned-patent to Christensen 'et al., extending to the oplerating handle 66. Bimetal titiiis connectedby two fiexcontact 54 follows under firm spring bias.

interrupted by shoulders 58.

ible lengths of metalrbraid od to the respective stabs of the dual plug-in terminal 48. These metal stabs each have lateral formations that are loosely complementary to formations in the molded insulating enclosure E2 and are accordingly movable flexibly in relation to each other. A red of insulation 69 project integrally from the wall of enclosure 52 to space stabs 48 and promote alignment with respective slots 34. in this Way, each stab can shift individually into proper plug-in contact engagement with terminal member 24 (FIG. 2).

A further feature contributing to the successful heavy current operation of the disclosed circuit breaker which is basically of the same small enclosure outline as the previous circuit breakers resides in the mounting of contact54 in relation to the companion contact 56 and its operating means. The operating linkage for contact arm 5? is made up of rigid elements, so that pressure of contact 56 against contact 54 is built up against spring 55. Circuit breakers of this type having an operating linkage of rigid elements is well known, as in Patent No. 2,209,351 issued July 30, 1940, to Joseph Sachs and in my Patent No. 2,923,795, issued February 2, l960,-assigned to the assignee of the present application. i

'As the moving contact swings down in the drawing,

Inasmuch as shoulder 53 at the right is higher than the other shoulder, the righthand edge'o'f the contacts part first, the spring maintaining the left-hand portion of contact. 54- in engagement with Its travel is contact 56. The parting of the contacts then starts arcing at the left, and the arc blows out toward the left, all of which acts to minimize the damage to the contacts result'mg from opening the contacts under load and particularly when carrying short-circuit current.

Closing of the contacts operates in reverse, the contacts engaging each other initially at the left-hand portion of the contacts and then shitting by a rocking or tilting of contact 54- until face contact is made. This action insures that that portion of the contact surfaces that have been least abused in the contact-making and breaking operations Will carry the operating current, resulting in cooler operation and lower contact resistance. The described movement of contact 54 is not inhibited by the casing that contains this spring-biased contact and which constrains or guides this contact against excessive lateral movement.

Each pole of the circuit breaker 46 includes the elements shown in FIG. 2. Inasmuch as the mechanism causing two-pole operation, that is, simultaneous opening of the contacts in response to a sin le-pole overload, forms no part of the present invention, little purpose apparently would be served by burdening the present specification with further details thereof. A single operating handle 66 for the coordinated side-by-side poles is shown in FIG. 1.

Circuit breaker panelboards normally include a trim plate which covers up the wiring and presents a neat finished appearance of the entire assembly. Trim plate 70 of standard design as shown in FIG. 2 has a hole 72 formed therein for accommodating the handle 66 of the circuit breaker 46, together with a protruding portion of the circuit breaker enclosure 52 that surrounds the operating handle. Trim plate 70 normally has a series of knockouts formed in the various places where the circuit breakers may project. However, inasmuch as the panelboard may be only partly filled with circuit breakers, these knockouts are left intact as parts of the trim plate in those areas where circuit breakers are not installed. In the case of the circuit breaker illustrated, which preempts the terminal portions 34 associated with both the righthand and t.e left-hand rows of circuit breaker receiving areas A, as shown in FIG. 1, the knockouts in trim plate 70 (at the right-hand side of the trim plate as viewed in FIG. 2) are left intact. The trim plate thus covers the areas 10A which are necessarily left empty because of the special construction of circuit breaker 46 which prevents additional circuit breakers from being received therein.

The circuit breaker enclosures 52 have a relief or cutout 53 in their otherwise generally rectangular outline, which accommodates the terminal bus assembly 14 While at the same time allowing the circuit breaker enclosures 52 to rest flush against the mounting pan It When a circuit breaker is to be installed, the circuit breaker is moved into engagement with one of the hooks 12 fitting into a recess 57 in the enclosure 52, the parts 12 and 57 functioning as a separable hinge to locate the circuit breaker both right-to-left in FIG. 2 and perpendicular to the view, so that the stabs 48 can be driven directly into slots 34. Trim plate '70 is assembled to the position in FIG. 2 after all the required circuit breakers have been mounted.

The circuit breaker .6 may obviously be used to energize a branch circuit which is thereby protected by the circuit breaker. However, particularly in pa elboards having space for receiving a large number of circuit breaker poles, the wires 74 shown connected to the screw terminals 54) of circuit breaker 46 might very well be the power supply line, circuit breaker 46 then serving as a main circuit breaker with the remainder of the circuit breakers on the panelboard then serving for branch-circuit protection.

While the embodiment illustrated and described above represents the presently preferred form of the invention, it is evident that it is natural y subject to a wide variety of modification in detail as well as varied application. Consequently the invention should be broadly construed, consistent with its full spirit and scope.

What is claimed is:

It. A circuit breaker for heavy current operation including a companion pair of contacts one of which is operable into and out of engagement with the other, including spring means for biasing said other contact toward the operable contact, guide means confining said other contact against excessive lateral motion, said guide means being free of restraining effect that would inhibit rocking of said other contact, and a pair of shoulders interposed in the path of said other contact when moving under spring bias so as to limit the movement thereof, said shoulders being at different levels relative to a plane of reference defined by the faces of the contacts when fully engaged and enforcing initial contact engagement and disengagement at one side of the contacts and rocking action during contact operation between initial engagement at one side and full face-to-face engagement, and said spring and shoulders providing firm contact pressure from the initial engagement of the contacts to their fully closed operating configuration and maintaining firm pressure until the instant of parting.

2. A circuit breaker in accordance with claim 1, including an operatin" linkage for said operable contact consisting of rigid elements.

3. A circuit breaker in accordance with claim 1, wherein said spring biasing means is a compression coil spring on the side of said other contact remote from said operable contact, further including a terminal connector and a flexible braid conductor connecting said connector to said other contact.

References Cited by the Examiner UNITED STATES PATENTS 10/47 Gay 200 4/60 Baker 200l50 BERNARD A. GILHEANY, KATHLEEN H. CLAFF Y,

Examiners, 

1. A CIRCUIT BREAKER FOR HEAVY CURRENT OPERATION INCLUDING A COMPANION PAIR OF CONTACTS ONE OF WHICH IS OPERABLE INTO AND OUT OF ENGAGEMENT WITH THE OTHER, INCLUDING SPRING MEANS FOR BIASING SAID OTHER CONTACT TOWARD THE OPERABLE CONTACT, GUIDE MEANS CONFINING SAID OTHER CONTACT AGAINST EXCESSIVE LATERAL MOTION, SAID GUIDE MEANS BEING FREE OF RESTRAINING EFFECT THAT WOULD INHIBIT ROCKING OF SAID OTHER CONTACT, AND A PAIR OF SHOULDERS INTERPOSED IN THE PATH OF SAID OTHER CONTACT WHEN MOVING UNDER SPRING BIAS SO AS TO LIMIT THE MOVEMENT THEREOF, SAID SHOULDERS BEING AT DIFFERENT LEVELS RELATIVE TO A PLANE OF REFERENCE DEFINED BY THE FACES OF THE CONTACTS WHEN FULLY ENGAGED AND ENFORCING INITIAL CONTACT ENGAGEMENT AND DISENGAGEMENT AT ONE SIDE OF THE CONTACTS AND ROCKING ACTION DURING CONTACT OPERATION BETWEEN INITIAL ENGAGEMENT AT ONE SIDE AND FULL FACE-TO-FACE ENGAGEMENT, AND SAD SPRING AND SHOULDERS PROVIDING FIRM CONTACT PRESSURE FROM THE INITIAL ENGAGEMENT OF THE CONTACTS TO THEIR FULLY CLOSED OPEATING CONFIGURATION AND MAINTAINING FIRM PRESSURE UNTIL THE INSTANT OF PARTING. 